Ethiopian officials have blocked social media sites across the country until the national school examination ends on Wednesday.
Facebook and other mobile apps have been disabled since Saturday, and citizens are complaining.
The government communications office said on Sunday that the blocking of sites is meant to ensure an "orderly exam process" that began on Monday.
An online leak of national exam sheets in May forced the tests to be postponed. Some opposition media claimed responsibility for the leaks.
Many have called it an embarrassment for the government.
Blogger Daniel Berhane says the government has no legal basis to deny the freedom of expression to millions of citizens. He says that "this is not China."
Ethiopia's Education Ministry says 254,000 students are expected to sit for the national exams.
